Stockholders' Deficit - Additional Information (Details)			1 Months Ended			6 Months Ended	12 Months Ended				16 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares	Oct. 29, 2015 shares	Oct. 31, 2015 $ / shares shares	Apr. 30, 2015 USD ($) shares	Aug. 31, 2014 USD ($) shares	Jul. 31, 2014 USD ($) shares	Dec. 31, 2016 USD ($) Vote $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) shares	Dec. 31, 2013 USD ($) shares	Dec. 31, 2013 USD ($) shares	Dec. 31, 2012 USD ($)
Class Of Stock [Line Items]
Preferred stock, shares authorized | shares	5,000,000						5,000,000	5,000,000
Preferred stock, par value | $ / shares	$ 0.0001						$ 0.0001	$ 0.0001
Preferred stock, shares issued | shares	0						0	0
Preferred stock, shares outstanding | shares	0						0	0
Change in fair value of redeemable convertible preferred stock call option liability								$ 314,000	$ 387,000
Cumulative cash dividend rate							8.00%
Dividends declared							$ 0
Accretion of convertible preferred stock value								98,000	$ 158,000
Gross proceeds from conversion of redeemable convertible preferred stock							$ 30,000,000
Redeemable convertible preferred stock converted ratio			367.50%
Voting rights, description							The holders of each share of convertible preferred stock have one vote for each share of common stock into which such convertible preferred stock may be converted.
Common stock, voting rights per share | Vote							1
Additional Paid-In Capital
Class Of Stock [Line Items]
Accretion of redeemable convertible preferred stock to redemption value								$ 500,000
Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Redeemable convertible preferred stock, shares authorized | shares			62,235,313						45,166,667
Redeemable convertible preferred stock, par value | $ / shares			$ 0.0001
Redeemable convertible preferred stock, shares outstanding | shares	0						0	0	44,916,667
Rights to purchase preferred stock shares at a discounted price							$ 40,000,000
Series A Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Redeemable convertible preferred stock, shares authorized | shares			38,500,000						38,500,000
Redeemable convertible preferred stock, par value | $ / shares			$ 0.0001
Redeemable convertible preferred stock, shares issued | shares						19,000,000					19,250,000
Net cash proceeds from issuance of redeemable convertible preferred stock						$ 19,000,000			$ 18,994,000		$ 19,200,000
Redeemable convertible preferred stock, shares outstanding | shares									38,250,000	19,250,000	19,250,000
Call option liability									$ 0			$ 500,000
Change in fair value of redeemable convertible preferred stock call option liability									15,000	$ 900,000
Reclassification of call option liability fair value to preferred stock upon issuance									300,000	$ 200,000
Issue price | $ / shares							$ 1.00
Cumulative dividends recorded	$ 6,300,000							$ 6,300,000
Accretion of redeemable convertible preferred stock to redemption value								73,000	$ 152,000
Conversion price | $ / shares							$ 1.00
Series A-1 Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Redeemable convertible preferred stock, shares authorized | shares			6,666,667						6,666,667
Redeemable convertible preferred stock, par value | $ / shares			$ 0.0001
Redeemable convertible preferred stock, shares issued | shares					6,666,667
Net cash proceeds from issuance of redeemable convertible preferred stock					$ 9,900,000				$ 9,896,000
Redeemable convertible preferred stock, shares outstanding | shares									6,666,667
Rights to purchase preferred stock shares at a discounted price							$ 40,000,000
Call option liability					$ 700,000				$ 300,000
Change in fair value of redeemable convertible preferred stock call option liability	0							300,000	400,000
Issue price | $ / shares							$ 1.50
Cumulative dividends recorded	1,000,000							1,000,000
Accretion of redeemable convertible preferred stock to redemption value								12,000	$ 6,000
Conversion price | $ / shares							1.50
Series B Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Redeemable convertible preferred stock, shares authorized | shares			17,068,646
Redeemable convertible preferred stock, shares issued | shares				17,068,646
Net cash proceeds from issuance of redeemable convertible preferred stock				$ 45,800,000				45,837,000
Issue price | $ / shares							2.695
Cumulative dividends recorded	$ 1,900,000							1,900,000
Accretion of redeemable convertible preferred stock to redemption value								$ 12,000
Conversion price | $ / shares							$ 2.695
IPO
Class Of Stock [Line Items]
Redeemable convertible preferred stock, shares issued | shares		6,253,125
IPO | Series A Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Redeemable convertible preferred stock, shares authorized | shares			38,500,000
IPO | Series A-1 Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Redeemable convertible preferred stock, shares authorized | shares			6,666,667
IPO | Series B Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Redeemable convertible preferred stock, shares authorized | shares			17,068,646